The present invention relates to a plasma display panel (PDP) and a method for manufacturing the same. In particular, this invention relates to a plasma display panel having improved partition walls forming numerous discharge cells and a method for forming the partition walls.
FIG. 4 is a perspective view showing the structure of an AC-type plasma display panel. In the drawing, reference numeral 1 represents a front glass substrate whose front surface serves as a display surface. A plurality of row electrode pairs (X, Y) extending in row direction (L direction, i.e., display line direction) are provided on the inner surface of the front glass substrate 1. One row electrode X of each row electrode pair (X, Y) includes i) a belt-like transparent electrode Xa consisting of a transparent electrically conductive film (such as ITO) and extending in row direction, and ii) a bus electrode Xb similarly extending in row direction and connected with the edge portions of the transparent electrode Xa. Similarly, the other row electrode Y of each row electrode pair (X, Y) includes i) a belt-like transparent electrode Ya consisting of a transparent electrically conductive film (such as ITO) and extending in row direction, and ii) a bus electrode Yb similarly extending in row direction and connected with the edge portions of the transparent electrode Ya. In this way, a plurality of the row electrodes X and a plurality of the row electrodes Y are arranged alternatively in column direction (R direction), with each row electrode pair (X, Y) forming an electric discharge gap therebetween.
Further, as shown in FIG. 5, a dielectric layer 2 is also formed on the inner surface of the front glass substrate 1 to cover up the row electrode pairs (X, Y). Here, the dielectric layer 2 is formed by applying to the inner surface of the glass substrate I an amount of glass paste having a low melting point, thereby forming a glass paste layer having a predetermined thickness. The glass paste layer is then subjected to a drying treatment and further by a sintering treatment at a predetermined temperature, thus forming the desired dielectric layer 2. Moreover, a protection layer 3 consisting of MgO is formed to cover the dielectric layer 2.
Referring again to FIG. 4, reference numeral 4 represents a back glass substrate disposed opposite to the front glass substrate 1, with an electric discharge space S formed therebetween. A plurality of column electrodes D are provided on the inner surface of the back glass substrate 4 and arranged in R direction, in a manner such that the column electrodes D are orthogonal to the row electrode pairs (X, Y). In practice, the plurality of column electrodes D are disposed in the same identical plane, parallelly spaced apart from one another at a predetermined interval.
Further, a plurality of stripe-like partition walls 5 extending in the column direction (R direction) are also arranged on the inner surface of the back glass substrate 4, with one partition wall disposed between every two adjacent column electrodes D. By virtue of the partition walls 5, the electric discharge space S is divided into a plurality of small spaces S, forming a plurality of discharge cells (smallest units of the display panel). Moreover, a plurality of fluorescent layers 6 extending in the column direction (R direction) are provided to cover exposed portions of the inner surface of the back glass substrate 4 as well as the side surfaces of each partition wall 5. In detail, the fluorescent layers 6 include R (Red), G (Green), B (Blue) layers arranged repeatedly in the display line direction L, with each color layer located between every two adjacent partition walls 5.
Subsequently, the front glass substrate 1 (carrying the row electrodes X, Y, the dielectric layer 2 and the protection layer 3) and the back glass substrate 4 (carrying the column electrodes D, the partition walls 5 and the fluorescent layers 6) are bonded together by means of a seat layer (not shown), thereby forming a plurality of discharge spaces S between the two glass substrates, as shown in FIG. 5.
Then, the discharge spaces S are vacuumized, and a mixed gas (such as Nexe2x80x94Xe gas or Hexe2x80x94Xe gas) capable of producing an ultraviolet light during electric discharge is sealed into the vacuum spaces. Afterwards, a plurality of module elements such as driver IC and the like are attached, thereby forming an AC-type plasma display panel (PDP).
FIG. 5 is a cross sectional view showing a cross section of the AC-type plasma display panel (PDP), taken along a line coincident with a row electrode pair (X, Y). As shown in FIG. 5, the partition walls 5 provided on the inner surface of the back glass substrate 4 are in contact with the protection layer 3, serving as spacers between the front glass substrate 1 and the back glass substrate 4, and defining a plurality of elongated spaces each containing a column electrode D. In this way, the plurality of column electrodes D as welt as the partition walls 5 are arranged to be orthogonal to the row electrode pairs (X, Y), forming a plurality of discharge cells C each serving as a unit luminescent area.
The operation of the AC-type plasma display panel (PDP) may be described as follows. At first, by virtue of address operation, electric discharges are effected in selected discharge cells C between the row electrode pairs (X, Y) on one hand and the column electrodes D on the other. As a result, lighting cells (cells having wall charges formed in the dielectric layer 2) and non-lighting cells (cells not having wall charges formed in the dielectric layer 2) are distributed on the panel, corresponding to an image being displayed on the display panel. After the address operation, discharge sustaining pulses are applied alternatively to the row electrode pairs (X, Y), effecting surface discharges in the lighting cells whenever the discharge sustaining pulses are applied. Thus, by virtue of the surface discharges in the lighting cells, ultraviolet lights are generated, rendering the R, G, B color fluorescent layers to emit corresponding color lights, thereby forming a color image on the display panel.
However, the above-described conventional AC-type plasma display panel has been found to have the following problem. Namely, a step of forming the plurality of partition walls is the most difficult step in the whole process for manufacturing the display panel. A representative method for forming the partition walls requires that an amount of glass paste containing a white pigment is applied to the inner surface of the back glass substrate, followed by a drying treatment so as to form a glass layer having a predetermined thickness. Afterwards, the glass layer is subjected to a sand blasting treatment with the use of a mask having a predetermined pattern, thereby selectively cutting and thus removing predetermined portions of the glass layer. Subsequently, a sintering treatment is carried out at a predetermined temperature, thereby forming a plurality of stripe-like partition walls 5 each having a rectangular or trapezoidal cross section.
Subsequently, an amount of fluorescent paste is applied so as to cover the side surfaces of the partition walls 5, the column electrodes D, as well as the exposed portions of the inner surface of the back glass substrate 4, followed by a sintering treatment for sintering the applied fluorescent paste, thereby forming a plurality of fluorescent layers 6 shown in FIG. 4 and FIG. 5.
With the above-described conventional plasma display panel, the formation of the fluorescent layer 6 on the side surfaces of the partition walls 5, the column electrodes D, as well as the exposed portions of the inner surface of the back glass substrate 4, can enable the fluorescent layers to have a sufficient total area and thus render the display panel to produce a sufficient brightness. However, as shown in FIG. 5, when the fluorescent layers 6 are formed in the above-described manner, each fluorescent layer""s portions a near the tops of adjacent partition walls 5 are thinner than other portions of the fluorescent layer 6, resulting in a problem that it is difficult for the plasma display panel to produce a sufficient brightness.
It is an object of the present invention to provide an improved plasma display panel and a method for manufacturing the same, in which each fluorescent layer""s portions near the tops of adjacent partition walls have a sufficient thickness, enabling the fluorescent layer within each discharge cell to have a substantially uniform thickness, thereby enabling the plasma display panel to produce a sufficient brightness.
According to the present invention, there is provided a plasma display panel which comprises a front substrate plate; a back substrate plate arranged opposite to the front substrate plate with an electric discharge space formed therebetween; a plurality of partition walls dividing the discharge space into a plurality of discharge cells; and a plurality of fluorescent layers each covering the bottom and side surfaces of each discharge cell. In particular, each of the partition walls has a T-shaped cross section.
In one aspect of the present invention, each partition wall includes a top portion having a dark or black color, and a main body portion having a light or white color.
In another aspect of the present invention, the width of the top portion is larger than the width of the main body portion, so that the top portion is protruding from the main body portion on both sides thereof.
In a further aspect of the present invention, each fluorescent layer""s portions located close to the top portions of adjacent partition walls have a thickness equal to the protruding extent of each top portion.
Further, according to the present invention, there is provided a method of manufacturing a plasma display panel which comprises: a front substrate plate; a back substrate plate arranged opposite to the front substrate plate, with an electric discharge space formed therebetween; a plurality of partition walls dividing the discharge space into a plurality of discharge cells; and a plurality of fluorescent layers each covering the bottom and side surfaces of each discharge cell. The method comprises the steps of: applying, to the inner surface of the back substrate plate, a first glass paste containing a predetermined amount of a binder and then a second glass paste containing a larger amount of a binder than the first glass paste, so as to form a first glass paste layer and a second glass paste layer which together will subsequently be formed into a plurality of partition walls; treating the second glass paste layer so as to form a mask corresponding to a pattern of the partition walls on the first glass paste layer, thus partially exposing the first glass paste layer; performing a sand blasting treatment on the exposed portions of the first glass paste layer, so as to selectively cut and thus partially remove the first glass paste layer; and sintering the first and second glass paste layers to form the plurality of partition walls.
In a still further aspect of the present invention, subsequent to the formation of the partition walls, internal spaces between the partition walls are filled with a fluorescent paste, followed by sintering the fluorescent paste, thereby forming a fluorescent layer in each of the internal spaces.
The above objects and features of the present invention will become better understood from the following description with reference to the accompanying drawings.